Disruption of the crypt niche promotes outgrowth of mutated colorectal tumor stem cells

Disruption of the β-catenin destruction complex via Ephexin1-Axin1 interaction promotes colorectal cancer proliferation

Wnt signaling is essential for cell growth and tumor formation and is abnormally activated in colorectal cancer (CRC), contributing to tumor progression; however, the specific role and regulatory mechanisms involved in tumor development remain unclear. Here, we show that Ephexin1, a guanine nucleotide exchange factor, is significantly overexpressed in CRC and is correlated with increased Wnt/β-catenin pathway activity. Through comprehensive analysis, including RNA sequencing data from TCGA and functional assays, we observed that Ephexin1 promotes tumor proliferation and migration by activating the Wnt/β-catenin pathway. This effect was mediated by the interaction of Ephexin1 with Axin1, a critical component of the β-catenin destruction complex, which in turn enhanced the stability and activity of β-catenin in signaling pathways critical for tumor development. Importantly, our findings also suggest that targeting Ephexin1 may increase the efficacy of Wnt/β-catenin pathway inhibitors in CRC treatment. These findings highlight the potential of targeting Ephexin1 as a strategy for developing effective treatments for CRC, suggesting a novel and promising approach to therapy aimed at inhibiting cancer progression.

Azoxymethane-induced carcinogenesis-like model of mouse intestine and mouse embryonic stem cell-derived intestinal organoids

BACKGROUND

Tumor modeling using organoids holds potential in studies of cancer development, enlightening both the intracellular and extracellular molecular mechanisms behind different cancer types, biobanking, and drug screening. Intestinal organoids can be generated in vitro using a unique type of adult stem cells which are found at the base of crypts and are characterized by their high Lgr5 expression levels.

METHODS AND RESULTS

In this study, we successfully established intestinal cancer organoid models by using both the BALB/c derived and mouse embryonic stem cells (mESCs)-derived intestinal organoids. In both cases, carcinogenesis-like model was developed by using azoxymethane (AOM) treatment. Carcinogenesis-like model was verified by H&E staining, immunostaining, relative mRNA expression analysis, and LC/MS analysis. The morphologic analysis demonstrated that the number of generated organoids, the number of crypts, and the intensity of the organoids were significantly augmented in AOM-treated intestinal organoids compared to non-AOM-treated ones. Relative mRNA expression data revealed that there was a significant increase in both Wnt signaling pathway-related genes and pluripotency transcription factors in the AOM-induced intestinal organoids.

CONCLUSION

We successfully developed simple carcinogenesis-like models using mESC-based and Lgr5 + stem cell-based intestinal organoids. Intestinal organoid based carcinogenesi models might be used for personalized cancer therapy in the future.

Murine models of colorectal cancer: the azoxymethane (AOM)/dextran sulfate sodium (DSS) model of colitis-associated cancer

Background

Colorectal cancer (CRC) is the third most common cancer. It is a heterogeneous disease, including both hereditary and sporadic types of tumors. CRC results from complex interactions between various genetic and environmental factors. Inflammatory bowel disease is an important risk factor for developing CRC. Despite growing understanding of the CRC biology, preclinical models are still needed to investigate the etiology and pathogenesis of the disease, as well as to find new methods of treatment and prevention.

Objectives

The purpose of this review is to describe existing murine models of CRC with a focus on the models of colitis-associated CRC. This manuscript could be relevant for experimental biologists and oncologists.

Methodology

We checked PubMed and Google from 01/2018 to 05/2023 for reviews of CRC models. In addition, we searched PubMed from 01/2022 to 01/2023 for articles using the azoxymethane (AOM)/dextran sulfate sodium (DSS) CRC model.

Results

Existing murine models of CRC include spontaneous, genetically engineered, transplantation, and chemically induced models. For the study of colitis-associated cancer (CAC), the AOM/DSS model is predominantly used. This model is very similar in histological and molecular characteristics to the human CAC, and is highly reproducible, inexpensive, and easy to use. Despite its popularity, the AOM/DSS model is not standardized, which makes it difficult to analyze and compare data from different studies.

Conclusions

Each model demonstrates particular advantages and disadvantages, and allows to reproduce different subtypes or aspects of the pathogenesis of CRC.

Cancer Stem Cell Relationship with Pro-Tumoral Inflammatory Microenvironment

Inflammatory processes and cancer stem cells (CSCs) are increasingly recognized as factors in the development of tumors. Emerging evidence indicates that CSCs are associated with cancer properties such as metastasis, treatment resistance, and disease recurrence. However, the precise interaction between CSCs and the immune microenvironment remains unexplored. Although evasion of the immune system by CSCs has been extensively studied, new research demonstrates that CSCs can also control and even profit from the immune response. This review provides an overview of the reciprocal interplay between CSCs and tumor-infiltrating immune cells, collecting pertinent data about how CSCs stimulate leukocyte reprogramming, resulting in pro-tumor immune cells that promote metastasis, chemoresistance, tumorigenicity, and even a rise in the number of CSCs. Tumor-associated macrophages, neutrophils, Th17 and regulatory T cells, mesenchymal stem cells, and cancer-associated fibroblasts, as well as the signaling pathways involved in these pro-tumor activities, are among the immune cells studied. Although cytotoxic leukocytes have the potential to eliminate CSCs, immune evasion mechanisms in CSCs and their clinical implications are also known. We intended to compile experimental findings that provide direct evidence of interactions between CSCs and the immune system and CSCs and the inflammatory milieu. In addition, we aimed to summarize key concepts in order to comprehend the cross-talk between CSCs and the tumor microenvironment as a crucial process for the effective design of anti-CSC therapies.

Colorectal cancer

Although surgery is the established standard and mainstay for treatment of colorectal cancer, advances in technology and clinical trials over the past 50 years have dramatically expanded and improved the detection, staging, treatment, and understanding of this disease. This review highlights contributions by surgeons, oncologists, gastroenterologists, engineers, and scientists to increase postsurgical recurrence-free survival, reduce the time and toxicity of treatment, and improve the quality of life for patients over the past half-century.

Colorectal cancer develops inherent radiosensitivity that can be predicted using patient-derived organoids

Identifying colorectal cancer patient populations responsive to chemotherapy or chemoradiation therapy before surgery remains a challenge. Recently validated mouse protocols for organoid irradiation employ the single hit multi-target (SHMT) algorithm, which yields a single value, the D0, as a measure of inherent tissue radiosensitivity. Here we translate these protocols to human tissue to evaluate radioresponsiveness of patient-derived organoids (PDOs) generated from normal human intestines and rectal tumors of patients undergoing neoadjuvant therapy. While PDOs from adenomas with a logarithmically-expanded Lgr5+-intestinal stem cell population retain the radioresistant phenotype of normal colorectal PDOs, malignant transformation yields PDOs from a large patient subpopulation displaying marked radiosensitivity due to reduced homologous recombination-mediated DNA repair. A proof-of-principle pilot clinical trial demonstrated that rectal cancer patient responses to neoadjuvant chemoradiation, including complete response, correlate closely with their PDO D0 values. Overall, upon transformation to colorectal adenocarcinoma, broad radiation sensitivity occurs in a large subset of patients that can be identified using SHMT analysis of PDO radiation responses.